Spray drying apparatus



UZ'- 301 19325 l e. B. vooRHnS 1,874,665

SPRAY DRYING' APPARATUS Filed March 7, 1930 IN VENT OR.

ffm/NAND 2B. Vooren/5 BY l ATTORNEYS.

Patented Aug. 30, 1932 f UNITED STATES'. PAIENI? oFFicE GRANTLANI) B. vooRIIIEs, on sAN FRANCISCO, CALIFORNIA, 'AssIGNoR To FEDERAL MILK coMrANxjo'F SAN FRANCISQGALIFORNIAA CORPORATION 0F NEVADA lsra-AY*I )RYING APPARATUS f Applicationv ined March 7,

This invention relates to `spray drying apparatus ofthe typeused drying milk in the manufacture of powdered milk, and the objects of the invention are to provide improvements in such apparatus whereby liquids of a.

stickier or more hygroscopic nature may be dried more efiiciently than with apparatus heretofore available.

The improvements are shown in the accompanying drawing in which the ligure isa vertical section taken through a spray drying box or room incorporating my improvements.

In the spray drying of milk and similar liquids various forms of drying boxes are used, the precise nature of the liquid or resulting dried product determining the size of box, regulation of air currents, heat, etc., and 1n the drying of milk, usually having some or all of its butter fat removed, the bulk of the powder falls by gravity and the lighter particles carried along on the hot air stream are intercepted on cloth screens or bags through which the air passes at the remote end of the box before the air is drawn out or finally disl charged from the box, and at the end of the run a workman enters the box to remove the powder which has piled up in the bottom as well as that which has accumulated upon the cloths.

However, in carrying out the process with material such as ice cream powder consisting of milk lincorporating sugar, gelatine, vegetable oils, etc., the resulting powder being relatively sticky will speedily choke the cloth screens at the nal end of the box so as to build up too much resistance for the proper flow of air to carry on the process, and the principal feature of my invention is the incorporating of auxiliary relatively coarse screens, preferably of metal mounted on rigid frames and which are arranged in a special way within the dying chamber and given periodic shocks to cause the powder to fall therefrom.

In the drawing the box 1 conveniently of about ten feet in height and about thirty or more feet in length, is provided with an inlet at 2 for large volume of heated air which is forced in from a source not shown and which is directed upward at an angle under 1930. Serial No. 434,039.

Y sand pounds per square inch and the ine particles robbed of their water are carried more or less horizontally toward the far end of the box toward final exit for the air at l which 1s subject to exhaustion from a fan not shown.

Most of the powder falls by gravity in the first two thirds of travel and the last third ofthe `box is partially separated by a partition 5 so that the air currents take an 11pward turn, then a downwardturn over the partition and then again upward through `cloth screens Gwhich are supported against coarse metal screens 7 and held tight thereagainst due tothe air pressure from within the loops or bags of cloth.

V When drying milk the forward part of the chamber usually contains no intercepting devices Abut when drying the more sticky powders mentioned l provide the specially pivoted screen frames 8, 9, l() and 11 pivoted on fixed horizontal axes l2, 13 and Mas indicated and each frame resiliently pulled at its freelend by aspring as at l5. sothat it will bear against a revolvable cam as at 16 shaped to permit the screen to snap back with a shock every time the high part of the cam rides over l c rlhese camsare on short shafts projecting throughthe side of the drying box or chaine ber and are preferably all geared together by any suitable means such as the chain 17 and sprockets 18 all slowly revolved as by a motor 1 9 provided with a wormQO operating on a gear Qliengaging a geaiQl". The screens are not lineenough to actually screen theparticles but are Vrelatively coarse about A16 mesh has been found satisfactory) as 'their function is to intercept or form a lighting place Aas it were for the passing pow der particles which, owing to their adherent nature quickly build up upon them, yet preserve freespaces for vpassage 0f air through the screens. f c

yThe arrangement shown with frames 8 and 9 standing vertically extending about half way down, and frames 10 andll inclined, has

been found satisfactory. It Vis understood 5' that the frames extend substantially across the entire chamber.

, tively large area no objectionable back presyover,'a screen in the sure is built u These cham ers are usually metal lined for easy Vcleaning and entry of a'person to remove the powder, all as well understood and not involvedin the present invention. U

' I claim:

,1. In a spray drying apparatus for mak-y ing powder from liquids and including a drying chamber, an intercepting screen within the chamber, and means for imparting a shock to said screen for droppingr accumulated powder therefrom, said screen being relatively coarse to afford an attaching place for adhesive powder only and not to serve as a medium for filtering the powder from the air currents. v

' 2. Ina spray drying apparatus for making powder from liquids and including a drying provided with doors for y ing powder from liqu drying of relatively sticky anules through each mesh of the screen for ree flow of air currents. t

6. kIn a vspray drying1 apparatus for maki sy including a drying chamber, anL intercepting screen within the chamber, said screen being relatively coarse .Y to ,affordA an attaching place for adhesive powder only and not to serve as a medium for filtering the powder from theair currents.

GRANTLAND B. VOORHIES.

chamber, a plurality of relatively rigidl f screensA extending generally up and `down and pivotally mounted at their upper edges in the chamber, said screens extending across the path of travel of the airfcurrents inthe chamber for intercepting the drying powder, and means for shocking the 'screensy to drop the powder therefrom. Y f

3.y A spray drying box comprising anelonated horizontally extending chamber, means or spraying the material to be dried into one end of the chamber, a artition partially isolating the remote end o? the chambery and forcing the air currents to make a turn thereforward portion ofthe chamberthrough which the powder-laden air travels, said screen being relatively coarse to afford an attaching place for adhesive powder only yand, notlr to serve as a mediumfor filtering the powder from thel air currents, and means in the remote lend of the chamber for filtering the air substantially free from powder. f i

4.A A spray 'drying box comprising an elongated horizontally extending chamber, means for 'spraying the material to'be dried into Y one end of the chamber, a partition partially isolatingthe remote end of the chamber and forcing the air currents to make a turn thereover, a pluralityy portiony of the chamber through which the powder-laden air travels arranged above the floors of the chamber, said screens being relaof yscreens in the forward f tively coarse to afford an attaching place for adhesive powder only and not to serve as a medium for filtering the powder from the air vcurrents,and means in the remote end 'of the chamber for filtering the airsubstan- 

